Sensor systems for the technical measuring determination of degrees of freedom of motion of the body and chassis in vehicles can be embodied in different ways, the determination of the degrees of freedom of motion being carried out, for example.                By measuring run or propagation times, i.e., by means of a sensor system, which is arranged in the area of the wheel suspension and/or the body, emits electromagnetic waves and determines a corresponding relative distance by the run/propagation time measurement in relation to a corresponding object. In principle, variables relative to a defined reference system, also derived over time, are possible. The technique can be used, for example, for the dynamic detection of the distance of the body from the road surface or also from a defined satellite position above the earth surface. Other degrees of freedom of motion, such as roll and pitch relative to the corresponding object, are also possible due to the arrangement of a plurality of sensors. The definition of the position of the body according to the GPS principle is, in general, not realistic at present for the vertical dynamic regulation of the body due to the requirements imposed on accuracy and the requirement imposed in terms of availability. By contrast, vehicle-mounted optoelectronic sensor systems are complicated and can therefore be used mainly for technical measuring tasks.        By relative measurement, i.e., by means of a sensor system, which is arranged in the area of the wheel suspension and/or the body and which determines the relative position between the transducer element and a sensor according to a magnetic or electrical principle of operation. The transducer and sensor are arranged at components of the wheel suspension and/or of the body, which components have variable positions in relation to one another. Since reproducible changes in position occur between these components during, for example, inward deflection motions of the wheel suspension, which changes in position can be considered to be proportional to the inward deflection path, the measured value of the sensor is used now for the determination of these variables by measurement. Possible principles are magnetoresistive sensors as well as Hall sensors, inductive or ohmic sensors.        By acceleration measurement, i.e., by means of seismically sensitive sensor systems, which represent an output signal proportional to the acceleration of the pick-up. The acceleration is an absolute variable in relation to a stationary inertial system, for example, the center of the earth. The absolute velocity can be determined by simple time integration, and the absolute position can be determined by repeated integration. Especially the latter is usually possible, due to the error of the sensor signal, with a great effort only by the use of special filtering techniques. In principle, the detection of great, high-frequency accelerations can be represented more easily than that of lower-frequency motions due to the small seismic mass of the sensor. If a plurality of sensors are used on different components, it is also possible to calculate the relative acceleration and the relative velocity between the components in a defined direction. Due to its principle of operation, the sensor itself is highly sensitive to stationary and dynamic changes in its axial position; however, this directional dependence of the sensor in relation to the field of gravity of the earth can also be used to determine angular positions in space in case of a corresponding arrangement and analysis algorithm.        
The above-described principles can be used for the determination of the primary states of motion of motor vehicles and for the determination of the corresponding states in passive and/or active chassis power elements.
EP 1 424 225 A2 discloses, for example, a bearing for a control arm of a wheel suspension of a vehicle, in which the bearing has at least one sensor, which is arranged in and on the bearing, and which determines the relative motion of the vehicle parts connected to one another by the bearing. This bearing can be used, in particular, to measure the level of the vehicle.
DE 103 33 997 A1 discloses a sensor array for a land vehicle with a body and at least one wheel, wherein the sensor array comprises a level sensor for measuring the relative position of the at least one wheel in relation to the body. The level sensor has electronic components, which are arranged in a housing, in which at least one acceleration sensor is provided. Furthermore, a land vehicle with a body and four wheels is disclosed, wherein one such sensor array each is provided between at least three of the wheels and the body.
A process for controlling the intensity of damping of an adjustable damper in a motor vehicle is known from U.S. Pat. No. 6,847,874 B2, in which the distance between a wheel and the vehicle body of the motor vehicle is measured with the use of distance sensors and a difference is formed from the distance sensor signals sent by these sensors. Damper velocity signals are determined from the difference of the distance sensor signals over a fixed time difference, and the damper velocity is determined from this. The damping intensity is controlled as a function of the damping velocity. A high-pass filter is used to filter out low frequencies below 2 Hz from the distance signals. Furthermore, the distance sensor signals are filtered by a low-pass filter, whose output signals are used to calculate the damper velocity signals. Already available sensors of a level control or of an air spring may be used as sensors, and the damper velocity is preferably determined for each wheel. The velocity of the vehicle body can be detected by means of an acceleration sensor mounted on same. As an alternative, the velocity of the vehicle body is determined from a damper velocity signal with the wheel velocity component filtered out.
However, the use of a body-side acceleration sensor combined with chassis-side distance sensors leads to an increased design effort and relatively high costs. Furthermore, the alternative determination of the velocity of the vehicle body from a damper velocity signal with the wheel velocity component filtered out is inaccurate.